Ankylosing spondylitis and undifferentiated spondyloarthropathies: a clinical review and description of a disease subset with older age at onset.

The onset of ankylosing spondylitis, as defined by the currently used criteria, after the age of 50 years is uncommon. Late-onset undifferentiated spondyloarthropathy is relatively more frequent. Its clinical spectrum seems to be as wide as it is in children and young and middle-aged adults. Most patients have two or more manifestations of spondyloarthropathy and meet the Amor criteria or the European Spondylarthropathy Study Group criteria. Some patients show only one manifestation of the B27-associated disease process for years and need more sensitive criteria. A subset of patients shows distal inflammatory swelling with pitting edema on the dorsum of feet or hands together with peripheral arthritis and peripheral enthesitis. In these cases spondyloarthropathy must be differentiated from other inflammatory rheumatic diseases with elderly onset showing the same distal inflammatory swelling with pitting edema.